I have had several users report the problem, but I am unable to find a solution at the moment. There is a high likelihood that the problem is due to web hosting servers preventing the plugin from retrieving the Pinterest RSS feed. Has anyone had success using other Pinterest plugins or have they all stopped working for you?

The problem is that Pinterest has begun blocking servers that it thinks are trying to harvest data from Pinterest.com. Most photo sharing website use APIs and are able to block a particular user from accessing the website, but Pinterest has not released an API. So instead of blocking a certain user, Pinterest blocks entire servers from accessing the RSS feed. If you are using a web-hosting company, it is likely that many dozens of websites share your server and any one of them could be responsible for getting the server blocked.